Aircraft gas turbofan engines operate at high temperature levels and therefore, turbine components and bearing cavities require efficient cooling, for example by air bled from the compressor of the engine. However, compressor air which is used to cool the turbine components and bearing cavities, has been heated by the compressor during the compression stage. Conventionally, an air-to-air heat exchanger is located in a bypass air duct of a turbofan gas turbine engine to capture a portion of a relatively cool bypass air flow to cool the relatively warmer compressor bleed air before the compressor bleed air is directed to various locations of the engine for cooling purposes. Such an air-to-air exchanger may be referred to as a buffer air cooler. However, a buffer air cooler disposed in a bypass air duct may cause flow resistance to the bypass air stream flowing through the bypass air duct and other issues affecting engine performance.
Accordingly, there is a need to provide an improved buffer air cooler system for turbofan gas turbine engines.